New domain: www.Speed-Talk.com

The forum is currently running on the new domain and server. The old domain will remain active for a short while to forward any (less frequent) visitors.
IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/

Ls 3 cylinder walls cracked

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Post Reply
sccagt1racer
New Member
New Member
Posts: 29
Joined: Wed Jul 13, 2016 9:22 pm

Ls 3 cylinder walls cracked

Post by sccagt1racer » Tue Sep 10, 2019 8:07 pm

Is it common for a ls3 bored to 4.070 to crack the cylinder walls vertically? #3 and #5 . The build is 11.2 to 1. cathedral port trick flow heads, ls6 intake, dry sump 7400 rpm's road race use. 450 hp 445tq at the rear wheels. It also has been losing the ground straps off the spark plugs. I suspect the tune has too much timing. Detonation?
You do not have the required permissions to view the files attached to this post.

peejay
Guru
Guru
Posts: 1774
Joined: Tue Aug 10, 2010 9:16 pm

Re: Ls 3 cylinder walls cracked

Post by peejay » Tue Sep 10, 2019 8:41 pm

sccagt1racer wrote:
Tue Sep 10, 2019 8:07 pm
Is it common for a ls3 bored to 4.070 to crack the cylinder walls vertically? #3 and #5 . The build is 11.2 to 1. cathedral port trick flow heads, ls6 intake, dry sump 7400 rpm's road race use. 450 hp 445tq at the rear wheels. It also has been losing the ground straps off the spark plugs. I suspect the tune has too much timing. Detonation?
The only time I ever lost the ground straps from the plugs, I was way off on the heat range because I didn't know any better, yet. Was running NGK 6-range plugs on an engine that needed -10s.

User avatar
needforspeed66gt
Guru
Guru
Posts: 2044
Joined: Sat May 06, 2006 6:18 pm

Re: Ls 3 cylinder walls cracked

Post by needforspeed66gt » Wed Sep 11, 2019 7:18 pm

Very uncommon, I see it with the LS7 blocks all the time, but only on one of the cast in place liner blocks if the tune was grossly off and resulted in nonstop detonation cycles. Look in through that water jacket passage and see if there's a crack in the aluminum right behind the cracked sleeve, the LS7 engines almost always crack both...the cylinder pressure spikes blow out the liner and the aluminum support for the sleeve cracks, then the actual liner cracks afterwards.
Nate
Engine Machinist

A_VAS
Pro
Pro
Posts: 202
Joined: Thu Dec 03, 2009 1:52 pm

Re: Ls 3 cylinder walls cracked

Post by A_VAS » Fri Sep 13, 2019 11:07 am

I've only seen that with LS2/3 blocks if a valve drops or piston chunk gets stuck between piston/head.

not seen it with detonation on engines that I know were detonated....so I'd say that's uncommon.

when I find a cracked one as mentioned, I save the blocks to use for Darton sleeving projects down the road
too lazy to make power w/o boost

sccagt1racer
New Member
New Member
Posts: 29
Joined: Wed Jul 13, 2016 9:22 pm

Re: Ls 3 cylinder walls cracked

Post by sccagt1racer » Fri Sep 13, 2019 3:38 pm

I got the engine fully torn down today. 6 out of 8 were cracked. The front cylinders were the only ones that were not cracked. The thrust side of the rod bearings have wear and the rest of the bearing looks normal. excessive detonation. The tune was not correct is what im going with on this one.

exhaustgases
Guru
Guru
Posts: 6107
Joined: Sun Oct 06, 2013 9:03 pm

Re: Ls 3 cylinder walls cracked

Post by exhaustgases » Fri Sep 13, 2019 6:12 pm

Just curious was this ever a problem with the old factory stock bore SBC I can't ever remember seeing that on one from detonation? So how thick are the cylinder walls? Where all the cracks oriented the same? And how? For and aft? Side to side?

Post Reply